Traditionally, variators for the mechanical computers that are used in fuel pumps have had the capacity for setting and posting unit prices in three digits, or places (i.e., 00.0.cent. to 99.9.cent.). With the advent in the United States of gasoline prices in excess of one dollar, and with similar occurrences and monetary changes elsewhere throughout the world, the demand has been created for variators of expanded capacity. Needless to say, the most pressing need has been for means by which existing pricing mechanisms can be retrofit to expand their capability from three to four places in the posted unit volume price.
The prior art has recognized and addressed this demand. For example, in U.S. Pat. No. 3,875,816, Wells suggests the use of a secondary gear stack to extend the range of a variator, utilizing the existing highest place range arm for selective engagement with the gears of either the primary or the secondary stack.
Smilgys et al disclose, in U.S. Pat. No. 4,136,573, the conversion of a fuel pump variator from a three-place to a four-place unit volume price, by adding an auxillary take-off assembly and an additional summation differential mounted coaxially above the cone gear. A selector or idler gear arrangement enables either a "0", a "1", or a "2" to be posted in the highest place position.
Devanney U.S. Pat. No. 4,292,506 teaches means for converting a fuel pump computer by employing a selective adder mechanism installed in the mechanical register, for manually adding either 50 cents or one dollar to a base unit volume price. German Offenlegungsschrift No. 2 232 375 is similar, in disclosing a fourth place mechanism that is integrated into the counter section of the computer.
A variator for four-place pricing is disclosed in German Offenlegungsschrift No. 24 60 430, which utilizes three summing mechanisms. One of the summing mechanisms receives the inputs from the two lower position units, the second receives the inputs from the two higher position units, and the third sums the inputs from the other two. The fourth place assembly, which is utilized to expand the capacity of the unit, is driven by a gear fixed on the input shaft, through an adapting gear having a reduction ratio that can be altered with exchangeable gears. German Auslegescrift No. 17 74 147 also appears to disclose a computer mechanism having four place capacity, as does French Patent No. 1,033,026.
In addition, mechanical computers having four-place price posting capability, and retrofit kits for expanding the capacity of three-place units, are commercially available. Despite all of such activity, a substantial need remains for means by which the capacity of a standard three-place unit volume price posting variator can be expanded to permit facile setting and posting of a four-digit price, wherein the highest order digit (i.e., the dollar place) is of selectively variable magnitude.
Accordingly, it is the principle object of the present invention to provide novel means in a variator by which the capacity for setting and posting the price can be expanded from three to four places, permitting facile selection of the magnitude of the added, highest-order digit.
It is also an object of the present invention to provide such means which can be retrofit into existing computer units.
A more specific object of the invention is to provide means of the foregoing nature which will permit the highest order place of the unit volume price to be selectively varied among five levels, enabling a price of from $0.000 to $4.999 to be posted, with the dollar setting automatically displayed.
Another object of the invention to provide such means which is relatively inexpensive to manufacture and facile to install, and will minimize any increase in torque loading and wear upon the parts of the unit.
Yet another object of the invention is to provide novel speed reduction mechanisms which permit decreases in the speeds of the output gears from the range arm assemblies, thereby further minimizing torque and undue wear of the parts.
A further object of the invention is to provide a novel variator having the foregoing features and advantages.